The Synthesis And Photocatalytic Performance Of Transition Metal Ions Modified G-C₃N₄ Material

Photocatalytic technology does a great favor by disposing the global problems of environmental pollution and energy shortage.Therefore,the design and synthesis of highly efficient photocatalytic materials has become the core in the photocatalysis research.Among them,graphite carbon nitride?g-C₃N₄?as a non-metallic visible light-response semiconductor catalyst can be applied to the photocatalytic applications for its intrinsic and unique properties.In this paper,g-C₃N₄ doped with three different transition mental ions,donated as Fe/g-C₃N₄,Co/g-C₃N₄ and Cu/g-C₃N₄,respectively,were designed and used to the photocatalytic degradation of rhodamine B?Rh B?.The microstructure,morphology and optical properties of the three materials were analyzed by means of multiple characterization methods,and the mechanism of the degradation of RhB was studied.First of all,the Fe/g-C₃N₄ photocatalytic was synthesized by mixing the few-layered g-C₃N₄ calcined for several times with reactable ionic liquid [Omim]FeCl₄.The structure,morphology and optical properties were analyzed by XRD,SEM,TEM,DRS and photocurrent measurement.XRD and XPS were used to determine the phase and composition of Fe/g-C₃N₄ materials,and it was proved that Fe doped into the crystal structure of g-C₃N₄ was in the form of Fe³⁺.Upon the visible light irradiation,the photocurrent value of Fe/g-C₃N₄ was significantly higher than that of pure g-C₃N₄,which indicated that the Fe/g-C₃N₄ photocatalysts had higher separation of the photogenerated electrons and holes pairs.The photocatalytic activity was evaluated by the degradation of RhB over Fe/g-C₃N₄ under visible light irradiation.Meanwhile,the effect of the Fe ions doping amount on the photocatalytic activity and the mechanism of the ehanced photocatalytic performance were investigated.Secondly,Co/g-C₃N₄ photocatalysts were obtained by stirring the few-layered g-C₃N₄ calcined for several times with reactable ionic liquid [Bmim]CoCl₄.The crystal structure,morphology,element composition and valance state were analyzed by XRD,TEM,XPS and DRS.At the same time,the influence of ion doping on the structural properties and photocatalytic performance of g-C₃N₄ photocatalysts was discussed in detail.The photocatalytic degradation of RhB over Co/g-C₃N₄ photocatalyst with different Co doping amount was investigated under visible light irradiation.The photocatalytic degradation mechanism of Co/g-C₃N₄ photocatalysts was investigated.Finally,with the aim to further improve the photocatalytic activity of g-C₃N₄,the Cu/g-C₃N₄ photocatalyst was successfully synthesized by incorporating copper ion into few-layered g-C₃N₄.The crystal structure,morphology,element composition and valance state were analyzed by multiple characterizations.The phase and composition of Cu/g-C₃N₄ photocatalyst was determined by XRD and XPS.The valance of Cu in the catalyst was in the form of Cu2+.Compared with pure g-C₃N₄,the photocurrent of Cu/g-C₃N₄ was enhanced,indicating that introducing Cu2+ species to g-C₃N₄ could reduce the recombination of electron and hole and improve the separation efficiency of electron hole pairs.The photocatalytic activity of pure g-C₃N₄ and Cu/g-C₃N₄ was investigated by RhB under visible light irradiation.The photocatalytic activity of Cu/g-C₃N₄ was higher than that of pure g-C₃N₄.Through the free radical trapping experiments,the synergistic effect of superoxide radical?O₂·-?,hydroxyl radical?·OH?and hole could improve the photocatalytic activity of Cu/g-C₃N₄.